Vacuum interrupter

Abstract

A vacuum interrupter envelope including a housing made of non magnetic metallic material with end plates fabricated from insulating material in the form of a ceramic or crystallized glass. Auxiliary sealing members are made of metallic material which are deformable in response to thermal stress at high temperture.

What is claimed is: 
     
       1. A vacuum interrupter comprising in combination: an envelope including a cylindrical housing made of a metallic material, a disc-shaped upper end plate made of an inorganic insulating material having an aperture in the center portion thereof and a disc-shaped lower end plate made of an inorganic insulating material having an aperture in the center portion thereof;   an electrical contact member including a stationary contact rod inserted into said envelope through said aperture of the upper end plate, a stationary electrical contact secured to said stationary contact rod, a movable contact rod inserted into said envelope through said aperture of the lower end plate and a movable electrical contact secured to said movable contact   a shielding member for shielding the inner surface of said envelope;   a first sealing means for sealing hermetically said upper end plate to said housing and including a first auxiliary sealing member made of a plastic deformable metallic material which is deformable by the thermal stress and a metallized portion provided between said first auxiliary sealing member and said upper end plate;   a second sealing member for sealing hermetically said lower end plate to said housing and including a second auxiliary sealing member made of a plastic deformable metallic material which is deformable by the thermal stress and a metallized portion provided between said second auxiliary sealing member and said lower end plate;   first supporting means for supporting and securing hermetically said stationary contact rod to said upper end plate including a metallized portion provided between said upper end plate and said stationary contact rod; and   hermetic seal means for sealing movably and hermetically said movable contact rod to said lower end plate including a bellows for securing said movable contact rod to said lower end plate and a metallized portion provided between said lower end plate and said bellows.   
     
     
       2. A vacuum interrupter as claimed in claim 1, wherein said first sealing means comprises an end portion of said housing, said first auxiliary sealing member secured to said end portion of said housing and a peripheral edge portion of said upper end plate secured to said first auxiliary sealing member via the metallized portion. 
     
     
       3. A vacuum interrupter as claimed in claim 1, wherein said second sealing means comprises the other end portion of said housing, said auxiliary sealing member secured to said other end of the housing and a peripheral edge portion of said lower end plate secured to said second sealing member via the metallized portion. 
     
     
       4. A vacuum interrupter as claimed in claim 1, wherein said first and second auxiliary sealing members of the first and second sealing means are made of Cu. 
     
     
       5. A vacuum interrupter as claimed in claim 1, wherein said first and second auxiliary members of said first and second sealing means are made of Fe. 
     
     
       6. A vacuum interrupter as claimed in claim 2, wherein said first sealing means comprises a stepped portion provided in an inner surface of one end portion of said housing, the first auxiliary sealing member having a ring-shaped flange portion and a tubular portion fitted into said stepped portion of said housing, and a ring-shaped projection formed in an outer edge portion of said disc-shaped upper end plate and secured to said flange portion of said first auxiliary sealing member by means of the metallized portion. 
     
     
       7. A vacuum interrupter as claimed in claim 3, wherein said second sealing means comprises a stepped portion provided in an inner surface of said other end portion of said housing, the second auxiliary sealing member having a ring-shaped flange and a tubular portion fitted into said stepped portion of the housing, and a ring-shaped projection formed in an outer edge portion of said lower end plate and secured to said flange portion of said second auxiliary sealing member by means of the metallized portion. 
     
     
       8. A vacuum interrupter as claimed in claim 1, wherein said first supporting means for supporting hermetically said stationary contact rod to said end plate further comprises a third auxiliary sealing member made of a non-magnetic material which is deformable by the thermal stress in brazing. 
     
     
       9. A vacuum interrupter as claimed in claim 8, wherein said third auxiliary sealing member is made of Cu. 
     
     
       10. A vacuum interrupter as claimed in claim 8, wherein said third auxiliary sealing member of said first supporting means is made of Fe. 
     
     
       11. A vacuum interrupter as claimed in claim 1, wherein said hermetic seal means comprises a bellows having an upper end secured to said movable contact rod and a lower end inserted into and secured to said aperture of said lower end plate by means of the metallized portion. 
     
     
       12. A vacuum interrupter as claimed in claim 8, wherein said third auxiliary sealing member of the first supporting means comprises a tubular portion inserted into and secured to the aperture of said upper end plate by the metallized portion and a flange portion secured hermetically to the upper end plate by means of the metallized portion. 
     
     
       13. A vacuum interrupter as claimed in claim 8, wherein said third auxiliary sealing member of the first supporting means comprises a first tubular portion secured to a stationary contact rod, a ring-shaped flat portion formed integrally with said first tubular portion and a second tubular portion formed integrally with said flat portion and secured to an inner surface of an upper end by means of a metallized portion. 
     
     
       14. A vacuum interrupter as claimed in claim 2, wherein said first sealing means comprises a stepped portion provided in an outer surface of one end portion of said housing, a tubular first auxiliary sealing member secured to said stepped portion of said housing and an outer circumferential surface of the upper end plate secured to an inner surface of said first auxiliary sealing member by means of a metallized portion. 
     
     
       15. A vacuum interrupter as claimed in claim 3, wherein said second sealing means comprises a stepped portion provided in an outer surface of the other end portion of said housing, a tubular second auxiliary sealing member secured to the stepped portion of said housing and an outer circumferential surface of the lower end plate secured to an inner surface of said second auxiliary sealing member by means of the metallized portion. 
     
     
       16. A vacuum interrupter as claimed in claim 1, wherein said shielding member comprises a first main arc-shield mounted on said stationary contact rod by means of a brazing material and a first auxiliary shield fixed to said first sealing member of said first sealing means, a second main arc-shield mounted on said movable contact rod, and a second auxiliary shield secured to said second auxiliary sealing member of said second sealing means, each of said shields is made of non-magnetic metallic material including an austenitic stainless steel. 
     
     
       17. A vacuum interrupter as claimed in claim 16, wherein said second auxiliary shield has a tubular portion secured to an inner surface of the lower end plate. 
     
     
       18. A vacuum interrupter as claimed in claim 17, wherein said second auxiliary shield has thermal stress releasing means for eliminating the thermal stress in brazing. 
     
     
       19. A vacuum interrupter as claimed in claim 18, wherein said thermal stress releasing means comprises a tapered portion provided in the tubular portion of said second auxiliary shield. 
     
     
       20. A vacuum interrupter as claimed in claim 18, wherein said thermal stress releasing means comprises an annular groove provided on the circumferential surface of the tubular portion of said second auxiliary shield. 
     
     
       21. A vacuum interrupter as claimed in claim 18, wherein said thermal stress releasing means comprises a plurality of axial slits provided along with the circumference of an open end portion of said tubular portion of the second auxiliary shield. 
     
     
       22. A vacuum interrupter as claimed in claim 17, wherein said first auxiliary shield is secured to an inner surface of said upper end plate, and said second auxiliary shield is secured to an inner surface of said lower end plate.